SOM-A
Rolled steel sheet is coated with an oil coating during production, requiring quality control of the spread oil volume. The SOM-A system measures the amount of oil spread on rolled steel or aluminum sheet, using the Hydrophil Balancing System.
Features
- Automatically detects the surface pressure to determine oil volume.
- LED displays the oil volume in mg/M3 or g/BB.
- Teflon coated trough allows easy washing and maintenance.
- Periodic calibration of balancing system can be done by user.
- Temperature control system ensures precise results in any environment.
Applications
- Oil volume of DOS, CSO, ATBC, etc. on rolled steel sheets
- Oil volume of DOS-A, etc. on rolled aluminum sheets
Measurement principle
Oil will spread over water in a monolayer if the area is large enough for the oil to spread freely. Since the density of one type of oil molecule is even, the oil volume should be in proportion to the area that the spread oil molecules occupy. Thus, if an even density of oil molecules is maintained, oil volume can be calculated from the occupied area.
How is an even density of oil molecules maintained?
Oil molecules raise surface pressure as molecules come close together. This property, called surface film pressure, is the reason oil molecules spread over water in a monolayer. (See Fig. 1.) The relation between the area occupied by oil and the surface film pressure follows a constant curve. (See Fig. 2.)
By specifying the surface film pressure, an even density of oil molecules can be maintained.
How do you measure Surface Film Pressure?
When the bottom of a detecting glass plate is immersed in subphase water, a meniscus (a phenomena of subphase wetting up to the plate surface) is formed as shown in Fig. 3. The oil molecules spread over water are arranged on the water surface and apply pressure to each other. This pressure pushes the glass plate upward.
